Download Honors Physics: Practice Problems for Midterm

Honors Physics:
1.
Practice Problems for Midterm
If A = 2i – 3j + 4k and B = 3i – 4j + 5k, find B – 2A.
2. A car with an initial velocity of 35 m/s west experiences a
constant acceleration of 3.0 m/s2 west for 30. s. a) During
this time, how far does it travel? b) If a 500. N force is
providing the acceleration, what is the rate at which the force
is doing work at the end of the 30. s? c) How far would it
travel in the same amount of time if the acceleration were in
the opposite direction?
3. A constant force of 22 N is exerted for 5.0 s on a 12 kg
object initially at rest. What is the change in speed of the
object?
4. A stone is thrown outward from the top of a 45.5 m cliff
with an upward velocity component of 18.0 m/s. a) How long
before the stone returns to its starting height? b) How long
is the stone in the air? c) What is the maximum height the
stone reaches? d) If the horizontal component of the velocity
is 12.0 m/s, how far from the cliff edge does the stone land?
e) What is the initial velocity of the stone?
5. A 15 g ball is released from rest 50. m above the Earth’s
surface. What is its velocity just before it hits the ground?
6. A 110.0 kg crate is pulled at constant speed along a
horizontal plane by a force of 330 N at an angle of 60.0º. a)
What is the coefficient of friction? b) If the crate is moved
5.0 m, what work is done? c) What is the average power if this
task is accomplished in 2.5 s?
7. A 12.0 kg crate slides down a 25.0º incline at constant
speed. What is the coefficient of friction?
8. The 12.0 kg crate is on the 25.0º incline where the
coefficient of static friction is 0.80. What is the maximum
force that can be applied parallel to the plane without moving
the crate?
9. A car is traveling at 45 m/s on a horizontal road. The
brakes are applied and the car skids to a stop in 30.0 s. What
is the coefficient of kinetic friction between the tires and
the road?
10. A 5 g object is whirled in a horizontal circle of radius
0.4 m at a constant speed of 2 m/s. What centripetal force is
required?
11. A worker pushes a 120 N crate 6.0 m upward along a
frictionless ramp that makes an angle of 25º with the
horizontal. If the force he exerts parallel to the slope
increases the speed of the crate at a rate of 1.75 m/s2, then
what is a) the increase in kinetic energy of the crate, b) the
increase in potential energy of the crate and c) the total work
done by the man?
12. What is the gravitational attraction between Cinnamon
(rest mass, 43.6 kg) and her bone (500 g), if they are 80.0 cm
apart? Which is greater, the attraction of Cinnamon to her
bone, or the attraction of the bone to Cinnamon? (P.S.
Cinnamon is snoring in her bed as I write this problem. It’s a
dog’s life!)
Answers:
1) -1i + 2j – 3k
2) 2400m; 62.5 kW; 300m East
3) 9.2 m/s
4) 3.68s; 5.40s; 62.0 m; 64.8 m; 21.6 m/s, 56.3º from x-axis
5) 31 m/s
6) .21; 830 J; 330 W
7) .47
8) 35.6 N down or 134 N up
9) .15
10) 0.05 N
11) 130 J; 300 J; 430 J
12) 2.27 X 10-9 N